According to U.S. Pat. No. 4,958,834, a golf stroke with a club that has a shaft that has been adjusted to compensate for the presence of a seam is likely to be more accurate and will achieve greater distance. As recognized in this patent, the task of determining the location of the seam in a metal shaft is important to accomplish the object of the invention. As a first approximation, the method disclosed in the aforementioned patent improves a club's performance by compensating for the presence of a seam with metal shafts that have a well-defined seam along the longitudinal axis of the shaft. As is well recognized, a golf swing is not an exact performance and any improvement in the club will assist a golfer generally or will reduce equipment-induced mis-hits.
The aforementioned patent describes a manual technique for determining the location of the seam in metal and composite shafts. It has become apparent, however, that this technique is only approximate and generally only locates the seam in a quadrant of the four quadrants present. With shafts made of carbon fibers and other composite materials, complications arise due to the manner in which these types of shafts are manufactured. For a large number of shafts, there is only a roughly defined seam. This results from the fact that for some shafts, several sheets of carbon fiber material are rolled typically by unskilled workers before setting the rolled sheets in an adhesive and prior to applying the surface coating. The effect is to make the definition or location of the effective seam difficult. Even were a worker to form a shaft using a single sheet of the carbon fibers, overlapping of the ends of the sheet can obscure the location of the effective seam. In this context, effective seam will be understood to mean a line extending longitudinally along the shaft surface that causes the shaft to bend and/or twist when used in a golf stroke irregularly when the effective seam is improperly positioned relative to the clubface. Of particular interest are the recently introduced filament wound shafts where a fiber strand is wrapped on a mandrel typically at a 45° angle to the axis of the mandrel with subsequent wraps being in the opposite direction as the previous wrap. Once the adhesive and the outer coating applied an effective seam still is detectable by the method this invention.